Fix #10758 Add compiler option to parse in strict mode

* add unit test to ensure "use strict" is not added twice
 * fix code

tests/cases/compiler/alwaysStrictAlreadyUseStrict.ts

@@ -0,0 +1,5 @@
+// @alwaysStrict: true
+"use strict"
+function f() {
+    var a = [];
+}